Facsimile communication system

ABSTRACT

Pixel information and control information transmitted by a facsimile machine  1   a  is received by a procedure controlling circuit  13  having a MODEM  13   a  for facsimile machines. A facsimile procedure controller  14  decodes the pixel information and the control information. A connection/transfer controller  15  edits the decoded information and produces a control packet and a pixel packet. The control packet and the pixel packet are output to a local area network (LAN)  4  via a LAN controller  17  and a LAN control circuit  18 . When receiving a facsimile, the control packet signal transmitted via the LAN  4  is converted into pixel control information by the connection/transfer controller  15 , and the pixel control information is supplied to the facsimile procedure controller  14 . The connection/transfer controller  15  also converts the received pixel packet signal into pixel information. The pixel information is temporarily stored in a memory  16 . When a predetermined amount of pixel information is accumulated in the memory  16 , said predetermined amount of pixel information is supplied to the facsimile procedure controller  14 , and finally transmitted to the facsimile machine  1   a  via the procedure control circuit  13.

This application is a divisional of application Ser. No. 09/421,353,which was filed on Oct. 18, 1999 now U.S. Pat. No. 6,285,466, which is adivisional of the parent application Ser. No. 09/082,609 which was filedon May 20, 1998 and is now abandoned.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to a facsimile communication apparatus forallowing a plurality of facsimile machines designed for generaltelephone networks to communicate with each other via a datacommunication network, such as a local area network (LAN), and to aprogram recording unit which stores a program used in the facsimilecommunication apparatus. This invention also relates to a facsimilecommunication apparatus for allowing a plurality of facsimile machinesto communicate with each other in real time via an Internet Protocolnetwork (referred to as an IP network) based on the IETF (InternetEngineering Task Force), and to a program recording unit storing aprogram for controlling the facsimile communication apparatus.

2. Description of the Related Art

FIG. 1 illustrates a conventional facsimile communication system using adata communication network, such as an LAN. The transmission sidefacsimile machine 1 is a G-3 facsimile machine designed for generaltelephone networks, which is categorized according to the T.30Recommendation standardized by the ITU-T (InternationalTelecommunications Union, Telecommunication Standardization Department).The facsimile machine 1 is connected to the facsimile communicationapparatus 10A via a telephone network 2. The facsimile communicationapparatus (i.e., the gateway) 10A converts the communication protocolbetween the telephone network 2 and the LAN 4. The LAN 4 is furtherconnected to another facsimile communication apparatus (i.e., gateway)10B, to which the receiving side facsimile machine 7 is connected via atelephone network 6. The facsimile machines 1 and 7 have the samestandard, and they can mutually transmit and receive image informationvia the telephone networks. The facsimile communication apparatus 10Bhas the same structure as the facsimile communication apparatus 10A, andthe explanation on it will be omitted.

As shown in FIG. 2, the facsimile communication apparatus 10A has aterminal accommodation circuit 3 a, to which a plurality of facsimilemachines 1 a through 1 n are connected via the corresponding telephonelines 2 a, 2 b, . . . , 2 n of the telephone network 2. The terminalaccommodation circuit 3 a is connected to a switch circuit 3 b whichselects the line which is currently requesting a facsimile transmissionfrom among the telephone lines 2 a through 2 n. A CODEC 3 c is connectedto the switch circuit 3 b in order to terminate the selected line. TheCODEC 3 c is a encoder/decoder which converts analog signals receivedfrom the telephone line 2 a into digital signals, and which decodesdigital signals into analog signals in order to output data to thetelephone line 2 a.

The terminal accommodation circuit 3 a, the switch circuit 3 b and theCODEC 3 c are connected to the CPU 3 e via a common bus 3 d. The CPU 3 econtrols the overall operations of the facsimile communication apparatus10A. A memory 3 f and a LAN control circuit 3 g are also connected tothe common bus 3 d. The memory 3 f temporarily stores digitizedinformation prior to transmitting the digitized information. The LANcontrol circuit 3 g performs data transfer in a packet format to andfrom another facsimile communication apparatus 10B via the LAN 4.

The facsimile machine 1 of FIG. 1 is connected to the facsimile machine7 via the telephone line 2, the facsimile communication apparatus 10A,the LAN 4, the facsimile communication apparatus 10B, and the telephoneline 6, in that order. If pixel information is transmitted from thefacsimile machine 1 a of FIG. 2 to the facsimile machine 7, the pixeldata read by the facsimile machine 1 a from the original document isencoded according to a prescribed coding rule. The encoded pixel data ismodulated by, for example, a 9600 bps MODEM installed in the facsimilemachine 1 a to produce an analog signal in the voice frequency band. Theanalog signal is transmitted to the facsimile communication apparatus10A through the telephone line 2 a. The CODEC 3 c of the facsimilecommunication apparatus 10A samples the analog signal supplied via thetelephone line 2 a based on a sampling signal of, for example, 8 KHz,and converts the sampled analog signal into an 8-bit digital signal foreach sampling.

Thus, the analog signal is converted into a 64 Kbps digital signal bythe CODEC 3 c, which is then read by the CPU 3 e via the common bus 3 d.The CPU 3 e edits the digital signal into a packet data of apredetermined size, and temporarily stores the packet data in the memory3 f. The packet data stored in the memory 3 f is read out by the LANcontrol circuit 3 g, and transmitted to the receiving side facsimilecommunication apparatus 10B via the LAN 4. In the facsimilecommunication apparatus 10B, the packet data received from the LANcontrol circuit 3 g is temporarily stored in a memory. Then, the storeddata is read out by a CPU corresponding to the CPU 3 e, and supplied toa CODEC corresponding to the CODEC 3 c, which converts the data into ananalog signal and outputs the analog signal to the facsimile machine 7via the telephone network 6. Thus, the analog signal transmitted fromthe facsimile machine 1 a is converted into a digital signal by theCODEC 3 c of the facsimile communication apparatus 10A, and transferredas a packet data to the receiving side facsimile communication apparatus10B via the LAN 4.

However, the conventional facsimile communication system has severalproblems.

Because the transfer path of the LAN 4 is divided into a plurality ofchannels in order to transfer the data in a packet format, the transferdelay time of the packet data is not constant. In addition, if thetraffic of the LAN 4 is heavy, the packet data may be lost half waythrough the transmission path. For these reasons, the analog signalswhich are being decoded by the CODEC 3 c of the receiving side facsimilecommunication apparatus 10B may sometimes be interrupted and, as aresult, wrong data is received by the receiving side facsimile machine7.

Furthermore, although the inherent data transfer rate between thefacsimiles machines 1 a and 7 is, for example, 9600 bps, the data istransferred at 64 Kbps in the LAN 4, which is inefficient from thestandpoint of data transfer capacity.

SUMMARY OF THE INVENTION

Therefore, the object of the invention is to overcome the problems inthe prior art, and to provide a facsimile communication system that canperform facsimile communication in an efficient manner from thestandpoint of data transfer capacity with little transfer errors.

In order to achieve the object, in the first aspect of the invention, afacsimile communication apparatus comprises: facsimile procedurecontroller that receives and transmits control information and pixelinformation from and to facsimile machines connected to the facsimilecommunication apparatus according to a predetermined procedure; a firstinformation converter that converts the control information and thepixel information received from the facsimile machines into a controlpacket signal and a pixel packet signal of predetermined formats; datatransmitter/receiver that transmits the control packet signal and thepixel packet signal produced by the first information converter via adata communication network, and that receives a control packet signaland a pixel packet signal transmitted via the data communicationnetwork; and a second information converter that converts the controlpacket signal and the pixel packet signal received by the datatransmitter/receiver into control information and pixel informationwhich are to be output to a receiving side facsimile machine. Thefacsimile communication apparatus may further comprise a memory whichstores a predetermined amount of pixel packet signals received by thedata transmitter/receiver and which outputs the stored signals to thesecond information converter when the predetermined amount of signalsare accumulated.

In the second aspect of the invention, a facsimile communicationapparatus comprises: means for calling the receiving side facsimilemachine based on a request for connection to the receiving sidefacsimile machine as received from the data communication network; meansfor temporarily storing the image data transmitted from the transmissionside facsimile machine via the data communication network in a memory;means for starting transmission of the image data to the receiving sidefacsimile machine when a data-receiving control signal representing theacceptability of image data is received from the receiving sidefacsimile machine, provided that a desirable amount of image data isstored in the memory at the time of receipt of the data-receivingcontrol signal; and waiting controller for transmitting a prescribedwait control signal to the receiving side facsimile machine in order tohave the receiving side facsimile machine stand by if the desirableamount of image data has not been stored in the memory at the time ofreceipt of the receiving control signal representing the acceptabilityof the image data from the receiving side facsimile machine.

In still another aspect of the invention, a program recording unit forstoring a program for controlling a facsimile communication apparatus isprovided. This program recording unit comprises: means for causing thefacsimile communication apparatus to call the receiving side facsimilemachine based on a request for connection to the receiving sidefacsimile machine received from the data communication network; meansfor causing the facsimile communication apparatus to temporarily storethe image data transmitted from the transmission side facsimile machinevia the data communication network in the memory; means for causing thefacsimile communication apparatus to start transmitting the image datato the receiving side facsimile machine when the facsimile communicationapparatus receives a data-receiving control signal that represents theacceptability of image data of the receiving side facsimile machine,provided that a desirable amount of image data is stored in the memoryat the time of receipt of the data-receiving control signal; and waitingcontroller for causing the facsimile communication apparatus to transmita prescribed wait control signal to the receiving side facsimile machinein order to have the receiving side facsimile machine stand by if thedesirable amount of image data has not been stored in the memory at thetime of receipt of the receiving control signal representing theacceptability of the image data from the receiving side facsimilemachine.

The waiting controller comprise determination means for determiningwhether or not the receiving side facsimile machine can stand by, whilemaintaining a data reception mode, if the desirable amount of image datahas not been accumulated in the memory at the time of receipt of thedata-receiving control signal. If it is determined that the receivingside facsimile machine can wait in the data reception mode, then waitingmeans causes the facsimile communication apparatus to wait for furtherstorage of image data until the desirable amount of image data is storedin the memory. On the other hand, if it is determined that the receivingside facsimile machine is not able to wait in the data reception mode,wait control signal transmitter causes the facsimile communicationapparatus to transmit the wait control signal to the receiving sidefacsimile machine.

The desirable amount of image data stored in the memory can becalculated by multiplying the transmission rate of the image datadetermined by negotiation between the transmission side facsimilemachine and the receiving side facsimile machine by a predetermined timestored in advance. Alternatively, the desirable amount of image data canalso be calculated by multiplying the communication rate determined bynegotiation between the transmission side facsimile machine and thereceiving side facsimile machine by a predetermined time stored inadvance. The transmission side facsimile machine and the receiving sidefacsimile machine are G3 facsimile machines categorized based on theT.30 Recommendation. In this case, the data-receiving control signal isa data-receivable state confirmation signal CFR according to the T.30Recommendation, and the wait control signal is a transmission siteidentification signal TSI according to the T.30 Recommendation.

The contents of patent application H9-131812 filed in Japan on May 22,1997 and a patent application filed in Japan on Apr. 22, 1998, theapplication number is not yet assigned, are incorporated hereinto byreference.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and objects will be apparent from the following detaileddescription with reference to the attached drawings, wherein:

FIG. 1 illustrates a conventional facsimile communication system;

FIG. 2 is a hardware block diagram of a conventional facsimilecommunication apparatus;

FIG. 3 is a hardware block diagram of the facsimile communicationapparatus according to a first embodiment of the invention;

FIG. 4 shows an example of control sequence of the facsimilecommunication apparatus of the first embodiment;

FIG. 5 shows an example of control sequence of the facsimilecommunication apparatus, which follows the control sequence shown inFIG. 4;

FIG. 6 is a hardware block diagram of the facsimile communicationapparatus according to a second embodiment;

FIG. 7 shows the facsimile communication sequence according to a thirdembodiment of the invention;

FIG. 8 is a flowchart showing the operation of the facsimilecommunication apparatus 10B according to a fourth embodiment; and

FIG. 9 is a hardware structural diagram of the facsimile communicationapparatus according to the fourth embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

1. First Embodiment

FIG. 3 illustrates the facsimile communication apparatus 10A accordingto the first embodiment of the invention. The facsimile communicationapparatus 10B has the same structure. The basic structure of the entirecommunication system that involves the facsimile communication apparatus10A and a plurality of facsimile machines is the same as that shown inFIG. 1, and the explanation will be omitted. A plurality of G3 facsimilemachines 1 a through 1 n, which are standardized according to ITU-TRecommendation T.30, are connected to the facsimile communicationapparatus 10A via the corresponding switchboard telephone lines 2 athrough 2 n. The facsimile machine 1 a reads pixel data from theoriginal, and encodes it according to a prescribed coding rule in orderto create pixel information PINF, which is then transmitted to areceiving side facsimile machine 7 via the telephone network 2. Thefacsimile machine 1 a also receives the pixel information PINF sent fromanother facsimile machine, and decodes it to reproduce the originalpixel data and to output the transmitted image. In addition to thetransfer of pixel data, the facsimile machine 1 a transmits and receivesseveral types of control information CINF to and from other facsimilemachines.

A part of the control information CINF is transferred as a tone signalof, for example, 1850 Hz, while the rest of the control information CINFand the pixel information PINF are transferred as, for example, 9600 bpsdigital signals. The 9600 pbs digital signal is modulated to produce avoice-band analog signal (of, for example, 1800 Hz carrier frequency) bythe MODEM built into the facsimile machine 1 a. This analog signal istransferred to and from the facsimile communication apparatus 10A viathe telephone line 2 a.

The facsimile communication apparatus 10A has a terminal accommodationcircuit 11 for connecting a plurality of facsimile machines 1 a through1 n via the telephone switchboard lines 2 a through 2 n. The terminalaccommodation circuit 11 is connected to a switch circuit 12, whichselects the line that is requesting facsimile transmission from amongthe telephone lines 2 a through 2 n. The switch circuit 12 is connectedto facsimile procedure controller (i.e., a procedure control circuit 13and a facsimile procedure controller 14), which terminates the selectedline.

The procedure control circuit 13 has a modem 13 a which has the samestandard as the built-in modem of facsimile machine 1 a. The modem 13 ademodulates the analog signal received from the telephone line 2 a toreproduce the original digital signal. The modem 13 a also modulates thedigital signal addressed to the facsimile machine 1 a to produce ananalog signal, and outputs the analog signal to the telephone line 2 a.The procedure control circuit 13 is connected to the facsimile procedurecontroller 14 which executes the transfer control procedure according tothe Recommendation T.30, as in facsimile machine 1 a.

In other words, the facsimile procedure controller 14 decodes thecontrol information CINF, which was sent from the facsimile machine 1 aand received by the procedure control circuit 13. Then, the facsimileprocedure controller 14 produces response control information CINF, andsends it back to the facsimile machine 1 a via the procedure controlcircuit 13. The control information CINF and the pixel information PINFthat are to be transmitted to the addressed facsimile machine 7 areoutput from the facsimile procedure controller 14 to the firstinformation converter (i.e., the connection/transfer controller) 15.

The connection/transfer controller 15 edits the control information CINFand the pixel information PINF supplied from the facsimile procedurecontroller 14 into packets of predetermined formats, and produces acontrol packet signal CPKT and a pixel packet signal PCKT which are tobe transmitted via the LAN 4. The connection/transfer controller 15 isconnected to a memory 16 for temporarily storing the generated controlpacket signal CPKT and pixel packet signal PCKT. When receiving afacsimile from another facsimile machine, the connection/transfercontroller 15 functions as a second information converter. That is,during the receiving operation, the control packet signal CPKT and thepixel packet signal PPKT sent via the LAN 4 are also temporarily storedin the memory 16. When the amount of received pixel packet signal PPKTreaches a predetermined amount, the connection/transfer controller 15reads out said predetermined amount of pixel packet signal PPKT,converts the pixel packet signal PPKT and the received control packetsignal CPKT into pixel information PINF and control information CINF,and output the pixel information PINF and the control information CINFto the facsimile procedure controller 14.

A data transmitter/receiver (that is, a LAN controller 17 and a LANcontrol circuit 18) are also connected to the connection/transfercontroller 15. The LAN controller 17 controls a protocol, such as TCP/IP(Transport Control Protocol/Internet Protocol), for data transfer to andfrom the LAN 4. The LAN controller 17 is connected to the LAN controlcircuit 18 which is physically connected to the LAN 4 in order totransmit and receive control packet signals CPKT and pixel packetsignals PPKT.

FIG. 4 shows a part of the control sequence of the facsimilecommunication apparatuses 10A and 10B, according to the firstembodiment, up to transmission of a sheet of pixel information. Eachelement of the facsimile communication apparatus 10A is denoted by anumerical symbol and a suffix A, while each element of the facsimilecommunication apparatus 10B is denoted by a numerical symbol and asuffix B. First of all, when a call-out signal is sent from thefacsimile machine 1 a to the facsimile communication apparatus 10A viathe telephone line 2 a (S50), the terminal accommodation circuit 11Adetects the call-out, and informs the connection/transfer controller 15Aof the occurrence of call-out. The connection/transfer controller 15Ainstructs the LAN controller 17A to connect to the LAN 4. Then, the LANcontroller 17A transmits an address inquiry signal based on TCP/IP tothe LAN 4 (S52).

When a confirmation response signal is returned to the facsimilecommunication apparatus 10A via the LAN 4 (S54), the facsimilecommunication apparatus 10A transmits a connection request signal to thereceiving side facsimile communication apparatus 10B (S56). Based onthis connection request, the facsimile communication apparatus 10B callsthe addressed facsimile machine 7 via the telephone line 6, and outputsa call-in signal to the facsimile machine 7 (S58). When the facsimilemachine 7 responds to the call-in signal, a response signal istransmitted to the facsimile communication apparatus 10B (S60). Uponreceiving this response signal from the facsimile machine 7, thefacsimile communication apparatus 10B transmits a call-connectionresponse signal to the facsimile communication apparatus 10A via the LAN4 (S62). Upon receiving the call-connection response signal, thefacsimile communication apparatus 10A sends a response signal to thefacsimile machine 1 a (S64). At this point in time, the facsimilemachine 1 a is connected to the facsimile machine 7 via the telephoneline 2, the facsimile communication apparatus 10A, the LAN 4, thefacsimile communication apparatus 10B, and the telephone line 6.

Then, the receiving side facsimile machine 7 successively transmits anon-standard function signal NSF, a called site identification signalCSI, and a digital identification signal DIS, which are portions ofcontrol information CINF, based on the ITU-T Recommendation T.30 (S66).The facsimile procedure controller 14B of the facsimile communicationapparatus 10B receives and decodes these signals, and supplies thedecoded signals to the connection/transfer controller 15B. Theconnection/transfer controller 15B edits these signals into a controlpacket signal CPKT (NSF/CSI/DIS), and transmits the control packetsignal to the LAN 4 via the LAN controller 17B and the LAN controlcircuit 18B (S68).

In the transmission side facsimile communication apparatus 10A, the LANcontrol circuit 18A receives the control packet signal CPKT(NSF/CSI/DIS) sent via the LAN 4, and outputs this control packet signalto the connection/transfer controller 15A via the LAN controller 17A.The connection/transfer controller 15A decomposes the control packetsignal (NSF/CSI/DIS) into three type of control information CINF,namely, a non-standard function signal NSF, a called site identificationsignal CSI, and a digital identification signal DIS. Then, thenegligible non-standard function signal NSF is abandoned, while thecalled site identification signal CSI and the diaital identificationsignal DIS are output to the facsimile procedure controller 14A.

The facsimile procedure controller 14A controls the procedure controlcircuit 13 so that it transmits the called site identification signalCSI and the digital identification signal DIS, which comprise controlinformation CINF, to the transmission side facsimile machine 1 a via thetelephone line 2 (S70). Upon receiving the called site identificationsignal CSI and the digital identification signal DIS transmitted fromthe receiving side facsimile machine 7, the facsimile machine 1 aoutputs a transmission site identification signal TSI and a digitalcommand signal DCS, which are control information CINF (S72).

When the control information CINF, which contains the transmission siteidentification signal TSI and the digital command signal DCS, isreceived by the facsimile communication apparatus 10A via the telephoneline 2, these signals are edited into a control packet signal CPKT(TSI/DCS), which is then transmitted to the facsimile communicationapparatus 10D via the LAN 4 (S74). The facsimile communication apparatus10B decomposes the received control packet signal CPKT (TSI/DCS) into atransmission site identification signal TSI and a digital command signalDCS, and successively transmits these signals to the facsimile machine 7via the telephone line 6 (S76). At this point in time, a facsimilecommunication link is established between the facsimile machines 1 a and7.

After the facsimile communication link is established, the transmissionside facsimile machine 1 a transmits a training check signal TCF, whichis control information CINF for training the pixel-information receivingmodem 13 a, to the facsimile communication apparatus 10A (S78). Thetraining check signal is used only in the analog-signal section, and itis not necessary for the LAN 4. Accordingly, when the training of themodem 13 a of the procedure control circuit 13A is completed, the modem13 a returns a confirmation return signal CFR, which is controlinformation CINF and informs of the fact that the modem 13 a is ready toreceive the pixel information, to the facsimile machine 1 a (S80). Thesame operation is performed in the receiving side facsimilecommunication apparatus 10B. The modem 13 a of the procedure controlcircuit 13B sends a training check signal TCF to the facsimile machine 7(S82). When the training of the modem of the facsimile machine 7 iscompleted, the facsimile machine 7 returns a confirmation responsesignal CFR to the facsimile communication apparatus 10B (S84). At thistime, the facsimile machine 1 a starts transmitting the pixelinformation PINF.

The pixel data read by the facsimile machine 1 a is encoded according tothe coding rule based on the recommendation T.30 to create pixelinformation PINF. The produced pixel information PINF is modulated toproduce an analog signal of the voice band by the 9600 bps modem builtinto the facsimile machine 1 a, and this analog signal is transmitted tothe facsimile communication apparatus 10A via the telephone line 2(S86). The received analog signal is demodulated into digital form bythe modem 13 a of the procedure control circuit 13. This demodulatedpixel information PINF is supplied to the connection/transfer controller15A via the facsimile procedure controller 14A, converted into a pixelpacket signal PPKT, and transmitted to the LAN 4 via the LAN controller17A and the LAN control circuit 18A (S88).

The pixel packet signal PPKT sent via the LAN 4 is received at the LANcontrol circuit 18B and the LAN controller 17B of the facsimilecommunication apparatus 10B, and is supplied to the connection/transfercontroller 15B. The connection/transfer controller 15B converts thepixel packet signal PPKT into pixel information PINF, and temporarilystores the pixel information PINF in the memory 16B. When the amount ofpixel information PINF accumulated in the memory 16B reaches apredetermined amount (for example, a data amount corresponding to apage), that amount of pixel information PINF is read out by thefacsimile procedure controller 14B, and is transmitted to the receivingside facsimile machine 7 by the procedure control circuit 13B via thetelephone line 6 (S90).

FIG. 5 shows the communication sequence following the sequence of FIG. 4(that is, after the completion of transmission of a page of pixelinformation from the facsimile machine 1 a). When the transmission sidefacsimile machine 1 a has transmitted a page of pixel information PINF,it generates a multi-page signal MPS, which is control information CINF(S92). The facsimile procedure controller 14A of the facsimilecommunication apparatus 10A decodes this control information CINF, andoutputs the decoded signal to the communication/transfer controller 15A.The communication/transfer controller 15A edits the multi-page signalMPS into a control packet signal CPKT (MPS), and outputs the controlpacket signal CPKT (MPS) to the LAN 4 via the LAN controller 17A and theLAN control circuit 18A (S94).

This control packet signal CPKT (MPS) sent via the LAN 4 is received atthe LAN control circuit 18B and the LAN controller 17B of the facsimilecommunication apparatus 10B, and is supplied to thecommunication/transfer controller 15B. The communication/transfercontroller 15B converts the received control packet signal CPKT (MPS)into a multi-page signal MPS, and outputs it to the facsimile procedurecontroller 14B. This multi-page signal MPS is output from the facsimileprocedure controller 14B to the receiving side facsimile machine 7 viathe procedure control circuit 13B and the telephone line 6 (S96). Uponreceiving the multi-page signal MPS, the facsimile machine 7 outputs amessage confirmation signal MCF, which is control information CINF, tothe facsimile communication apparatus 10B (S98).

The facsimile communication apparatus 10B edits the message confirmationsignal MCF into a control packet signal CPKT (MCF), and transmits it tothe facsimile communication apparatus 10A via the LAN 4 (S100). Thefacsimile communication apparatus 10A converts the received controlpacket signal CPKT (MCF) into a message confirmation signal MCF, andtransmits it to the facsimile machine 1 a via the telephone line 2(S102). Upon receiving the message confirmation signal MCF, thefacsimile machine 1 a starts transmitting the pixel data of the nextpage as the pixel information PINF in the same manner as the first pagewas transmitted.

When the facsimile machine 1 a is finished transmitting all the pixelinformation PINF, the facsimile machine 1 a outputs an end-of-proceduresignal EOP, which is control information CINF (S110). The facsimilecommunication apparatus 10A edits this end-of-procedure signal EOP intoa control packet signal CPKT (EOP), and sends the control packet signalCPKT (EOP) to the facsimile communication apparatus 10B via the LAN 4(S112). Upon receiving the control packet signal CPKT (EOP), thefacsimile communication apparatus 10B converts this packet signal intoan end-of-procedure signal EOP, and sends it to the receiving sidefacsimile machine 7 via the telephone line 6 (S114). When the facsimilemachine 7 receives the end-of-procedure signal EOP, it returns a messageconfirmation signal MCF (S116-S120).

When the facsimile machine 1 a receives the message confirmation signalMCF from the facsimile machine 7, it generates a disconnection commandsignal DCN, which is control information CINF (S122) The facsimilecommunication apparatus 10A edits the disconnection command signal DCNinto a control packet signal CPKT (DCN), and transmits it to thefacsimile communication apparatus 10B via the LAN 4 (S124). Thefacsimile communication apparatus 10B converts the control packet signalCPKT (DCN) into a disconnection command signal DCN, and sends it to thereceiving side facsimile machine 7 via the telephone line 6 (Sl26). Atthis point of time, facsimile communication between the facsimilemachines 1 a and 7 is finished.

After finishing the communication, the facsimile machines 1 a and 7disconnect themselves from the telephone lines 2 and 6, respectively(S128). These disconnected states are reported to the facsimilecommunication apparatuses 10A and 10B, whereby the facsimilecommunication apparatuses 10A and 10B disconnect themselves from the LAN4 (S130). As has been described above, each of the facsimilecommunication apparatuses 10A and 10B has a procedure control circuit 13having a modem 13 a, which is the same standard as the facsimile machine1 a, and a facsimile procedure controller 14 which executes a transfercontrol procedure according to the recommendation T.30.

These elements allow the control information CINF and the pixelinformation PINF to be transferred between the facsimile machine 1 a andthe facsimile communication apparatus 10A according to the facsimileprocedure, and they also allow the control packet signal CPKT and thepixel packet signal PPKT to be transferred between the facsimilecommunication apparatuses 10A and 10B according to the procedure of theLAN 4. Transmitted data is temporarily stored in the memory, and apredetermined amount of data is output to the receiving side facsimilemachine. Thus, facsimile communication is achieved via datacommunication networks, such as the LAN 4, with little transmissionerrors and by efficiently using transfer capacity.

2. Second Embodiment

FIG. 6 is a hardware block diagram of the facsimile communicationapparatus 10A according to the second embodiment of the invention. Thefacsimile communication apparatus 10B also has the same structure asthat shown in FIG. 6. In this embodiment, the facsimile communicationapparatus 10A has a CPU 37 in place of the facsimile procedurecontroller 14, the LAN controller 17, and the communication/transfercontroller 15. The facsimile communication apparatus 10A also has aCD-ROM driver 34 for reading out a program from a CD-ROM 36, and a harddisc drive 38 for storing the program read out from the CD-ROM 36. Theprogram stored in the hard disc drive 38 is read out by the memory 16,and is executed. In this specification and in the appended claims,portable recording media including the CD-ROM 36, fixed storingapparatuses including the hard disc drive 38, and volatile storingdevices including the memory 16 are all referred to as program recordingunits.

The program stored in the program recording unit may be executeddirectly by the CPU 37, or it may be decoded prior to being executed bythe CPU 37 if it is stored in an encoded format. The program stored inthe CD-ROM 36 has program modules for causing the CPU 37 to execute theoperations performed by the facsimile procedure controller 14, theconnection/transfer controller 15, and the LAN 4, shown in FIG. 3. Basedon these program modules, the CPU 37 performs the same operations as thefacsimile communication apparatus 10A shown in FIGS. 3 thru 5. In thisembodiment, the operations of the facsimile communication apparatus 10Acan be easily changed by simply changing the CD-ROM 36.

3. Third Embodiment

In the third embodiment, an IP network (Internet Protocol network) 50according to the IETF (Internet Engineering Task Force) is used as thedata communication network in place of the LAN 4 shown in FIG. 1. The“IP network” includes both the Internet and intranets. The facsimilecommunication apparatus 10A according to this embodiment has an IPnetwork control circuit and an IP network controller in place of the LANcontrol circuit 18 and the LAN controller 17 shown in FIG. 3. The otherhardware structure is the same as that shown in FIG. 3, and theexplanation will be omitted.

FIG. 7 shows a part of the control sequence of the facsimile machine 1a, according to the third embodiment, up to transmission of a sheet ofpixel information to the facsimile machine 7. The facsimile machines 1 aand 7 are connected to the facsimile communication apparatuses 10A and10B via the telephone lines 2 and 6, respectively, as in the firstembodiment. when the facsimile communication apparatus 10A receives arequest for connection to the facsimile machine 7 from the facsimilemachine 1 a (S200), the facsimile communication apparatus 10A accessesthe address information storing device 16 (S202) to obtain the IPaddress of the facsimile communication apparatus 10B, to which thefacsimile machine 7 is connected (S204). Then, the facsimilecommunication apparatus 10A requests the facsimile communicationapparatus 10B to connect itself to the facsimile machine 7 (S206). Inresponse to this request, the facsimile communication apparatus 10Bconnects itself to the facsimile machine 7 (S208 and S210). Upon theestablishment of the connection between the facsimile communicationapparatus 10B and the facsimile machine 7, the facsimile communicationapparatuses 10A and 10B cooperate to provide a communication pathbetween the facsimile machines 1 a and 7.

As in the first embodiment, when the facsimile machine 1 a receives aconnection response signal (S212 and S214), followed by a non-standardfunction signal NSF, a called site identification signal CSI, and adigital identification signal DCS (S216 through S220), from thefacsimile machine 7 via the facsimile communication apparatuses 10A and10B, the facsimile machine 1 a transmits a transmission siteidentification signal TSI, a digital command signal DCS, and a trainingcheck signal TCF (S222). Then, upon receiving a receipt-readyconfirmation signal CFR from the facsimile communication apparatus 10A(S224), the facsimile machine 1 a starts transmitting the pixel data(S230). Prior to this, the facsimile communication apparatus 10Atransfers the transmission site identification signal TSI and thedigital command signal DCS to the facsimile communication apparatus 10B(S226) upon transmitting the receipt-ready confirmation signal to thefacsimile machine 1 a (S224).

While the facsimile machine 1 a is transmitting the pixel data (S230),the receiving side facsimile communication apparatus 10B and thefacsimile machine 7 are transferring control signals to each other (S228and S234 through S242). In other words, the receiving side facsimilecommunication apparatus 10B stores the pixel data sent from thefacsimile machine 1 a via the facsimile communication apparatus 10A inthe memory 3 f, while it transfers control signals to and receivescontrol signals from the facsimile machine 7 (S232).

The facsimile communication apparatus 10B starts transferring the pixeldata to the facsimile machine 7 after a predetermined amount of pixeldata has been stored in the memory (S246) in order to avoid undesirableinterruption of the communication between the facsimile machines 1 a and7, which generally occurs due to a transfer delay arising in the IPnetwork 50. Prior to this, if a predetermined amount of data has notbeen accumulated in the memory when the facsimile communicationapparatus 10B receives the receipt-ready confirmation signal CFR (S242),the negotiation sequence—that is, transmission of the transmission sideidentification signal TSI, the digital command signal DCS, and thereceipt-ready confirmation signal CFR to the facsimile machine 7 (S230through S242)—is repeated in order to gain time for further accumulationof pixel data in the memory 3 f.

According to the third embodiment, the facsimile communication apparatus10B can start transmission of pixel data after a sufficient amount ofpixel data is accumulated in the memory 3 f. Accordingly, even if thecommunication rate of the IP network 50 drops due to an increase intraffic, the facsimile communication apparatus 10B can continuouslyconvert the pixel data read out from the memory 3 f into analog signalsand transmit them to the facsimile machine 7 at a constant rate. If thepixel data is lost, the lost data can be retransmitted to the facsimilecommunication apparatus 10A, during which the pixel data read out fromthe memory 3 f are continuously transmitted to the receiving sidefacsimile machine 7 without cutting off communication. Thus, thisarrangement can prevent an unexpected shutoff of the communicationbetween the facsimile communication apparatus 10B and the facsimilemachine 7 due to a decrease in communication rate or data loss.

4. Fourth Embodiment

In the previous embodiment (i.e., the third embodiment), the facsimilecommunication apparatus 10B stores a predetermined amount of pixel datain the memory 3 f. However, if the communication rate between thefacsimile communication apparatus and the facsimile machine 7 isrelatively slow, it takes time to transmit the pixel data stored in thememory 3 f to the facsimile machine 7. In such a case, it is notnecessary to store a great amount of pixel data in the memory 3 f. Inview of this, too much pixel data in excess of a desirable amount mayoccasionally be accumulated in the memory in the third embodiment. Inaddition, a sequence lag which generally arises between the transmissionside facsimile machine 1 a and the receiving side facsimile machine 7becomes large and, as a result, a communication error is likely to occurin the transmission side facsimile machine 1 at a page boundary due toresponse wait time-out.

Furthermore, in the third embodiment, the facsimile communicationapparatus 10B repeats the negotiation sequence (S212 through S216) if apredetermined amount of pixel data has not been accumulated in thememory at the time of receipt of a CFR from the receiving side facsimilemachine 7. During this negotiation sequence, too much pixel dataexceeding the desirable amount is accumulated because the negotiationsequence generally takes time. This also causes a sequence lag betweenthe transmission side facsimile machine 1 a and the receiving sidefacsimile machine 7, and the time when the receiving side facsimilemachine 7 has fully received a page of pixel data is delayed. As aresult, a communication error may occur at a page boundary in thetransmission side facsimile machine 1 a due to response wait time-out.In order to overcome these problems, a real-time facsimile communicationsystem which can absorb a delay in the IP network and allow stable andhighly successful communication is provided in the fourth embodiment.

FIG. 8 shows the operation flow of the facsimile communication apparatus10B according to the fourth embodiment. The facsimile communicationapparatus 10B has a standard hardware structure as in the thirdembodiment. When the facsimile communication apparatus 10B receives arequest for connection to the facsimile machine 7 from the facsimilecommunication apparatus 10A, it informs the facsimile machine 7 of theoccurrence of call-in, and connects itself to the facsimile machine 7(S300). Then, the facsimile communication apparatus 10B reads thecommunication rate between the facsimile machines 1 and 7 from thecontrol signal DCS received from the facsimile machine 1 a, andcalculates the minimum amount of pixel data that must be stored in thememory in order to continuously transmit the pixel information to thefacsimile machine 7 for a predetermined period of time (S302). Then, thefacsimile communication apparatus 10B transmits a transmission siteidentification signal TSI, a digital command signal DCS, and a trainingcheck signal TCF to the facsimile machine 7 for the purpose ofcommunication training with the facsimile machine 7 (S304). When thefacsimile communication apparatus 10B receives pixel data from thefacsimile communication apparatus 10A (S306), it stores the pixel datain the memory 3 f (S308).

If the facsimile communication apparatus 10B has already received acontrol signal CFR from the facsimile machine 7 (S310), it determines ifthe minimum necessary amount of pixel data calculated in S302 has beenaccumulated in the memory 3 f (S312) If so, the facsimile communicationapparatus 10B starts transmitting the pixel data to the facsimilemachine 7 (S314). Meanwhile, the receiving side facsimile machine 7transmits a receiving-ready confirmation signal CFR, and if it does notreceive any pixel data even after a predetermined period of time T haspassed since the transmission of the receiving-ready confirmation signalCFR, it again transmits a non-standard function signal NSF according tothe Recommendation T.30. The facsimile communication apparatus 10Bstores the predetermined time T (from the transmission of thereceiving-ready confirmation signal CFR to immediately before thetransmission of the non-standard function signal NSF) in advance. If theminimum necessary amount of pixel data has not been accumulated in thememory in S312, the facsimile communication apparatus 10B determineswhether said predetermined time T has already elapsed (S316).

If time T has not passed yet in S316, the process returns to S306, andthe pixel data is continuously stored in the memory 3 f. If time T hasalready passed in S316, the facsimile communication apparatus 103 sets aflag that represents the receiving sate of the receiving-readyconfirmation signal CFR to “No Receipt” (S318), and the process returnsto the training sequence (S304). Accordingly to this operation flow, thecommunication procedure does not have to return to the transmission ofthe non-standard function signal NFS, and the facsimile machine 7 canstart receiving the pixel data earlier.

FIG. 9 illustrates an example of software function of the facsimilecommunication apparatus 10B according to the fourth embodiment of theinvention. The facsimile communication apparatus 10B has an executingunit 22 a and a data unit 22 b as structural elements of the software.The executing unit 22 a comprises an IP communication controller (IPC)30, an IP data analyzer (DAL) 31, a facsimile communication controller(FCL) 32, a pixel data storage controller (STM) 33, and a timingcontroller (TQM) 34. The data unit 22 b comprises a pixel data storage40 and a pixel data storage amount manager 41. The pixel data storage 40stores pixel data information together with data representing thecurrent storage amount of pixel data. The pixel data storage amountmanager 41 stores the optimum transmission time that is converted fromthe optimum storage amount of pixel data. The facsimile communicationapparatus 10A has the same structure as the facsimile communicationapparatus 10B, and further explanation will be omitted.

The operation of the major elements of the receiving side facsimilecommunication apparatus 10B, which are performed during the operationflow shown in FIG. 8, will be explained with reference to FIG. 9. Whenthe IP communication controller 30 receives IP data from thetransmission side facsimile communication apparatus 10A via the IPnetwork 50, it requests the IP data analyzer 31 to analyze the IP data.If the received IP data is a T.30 signal consisting of control signalsTSI and DCS as a result of the analysis, the IP data analyzer 31requests the facsimile communication controller 32 to send this IP datato the facsimile machine 7. The facsimile communication controller 32transfers the control signals TSI and DCS to the facsimile machine 7and, at the same time, it obtains from the DCS the communication rate ofthe facsimile communication which is to take place in this sequence, andreports the communication rate to the pixel data storage controller 33.

On the other hand, if the received IP data is pixel data, then the IPdata analyzer 31 requests the pixel data storage controller 33 totemporarily store this IP data. In response to this request, the pixeldata storage controller 33 stores the IP data in the pixel data storage41 and, at the same time, it updates the storage amount information. Thepixel data storage controller 33 reads out the optimum data transmissiontime from the pixel data storage manager 41, calculates the optimumamount of pixel data that should be stored by multiplying thecommunication rate by the optimum transmission time, and stores thisoptimum value in the pixel data storage manager 41. When the facsimilecommunication controller 32 receives the CFR from the receiving sidefacsimile machine 7, it inquires of the pixel data storage controller 33as to whether or not the optimum amount of pixel data has already beenstored.

The pixel data storage controller 33 reads out the optimum pixel-datastorage amount from the pixel data storage manager 41 and, at the sametime, it reads the amount of pixel data that has been stored in thepixel data storage 40 by that point of time and compares it with theoptimum value. If the optimum amount of pixel data has already beenaccumulated, the pixel data storage controller 33 informs the facsimilecommunication controller 32 that the pixel data can now be transmitted.The facsimile communication controller 32 requests the pixel datastorage controller 33 to read out the pixel data, and it startstransferring the pixel data to the facsimile machine 7. On the otherhand, if the optimum amount of pixel data has not been accumulated inthe comparison step, then the facsimile communication controller 32instructs the timing controller 34 to restart the facsimilecommunication controller 32 after a predetermined time interval, and theprocess is interrupted.

The timing controller 34 restarts the facsimile communication controller32 after a predetermined time, and the facsimile communicationcontroller 32 again inquires of the pixel data storage controller 33 asto whether the optimum amount of pixel data has been accumulated. Thesesteps are repeated until the optimum amount of pixel data has beenaccumulated in the data storage 40. During the interruption, thefacsimile communication controller 32 does not transmit any signals orpixel data to the receiving side facsimile machine 7.

If no pixel data is transmitted to the receiving side facsimile machine7, even after a predetermined period of time has passed since thetransmission of the receiving-ready confirmation signal CFR, thefacsimile machine again transmits a non-standard function signal NSFaccording to the Recommendation T.30. The timing controller 34 stores inadvance the time T from the transmission of the receiving-readyconfirmation signal to immediately before the transmission of thenon-standard function signal NSF, and if time T has elapsed, it informsthe facsimile communication controller 32 of the time limit. Then, thefacsimile communication controller 32 restarts from the step oftransmitting a transmission site identification signal TSI to thereceiving side facsimile machine 7, and allows the pixel data to becontinuously stored. This operation flow can allow the receiving sidefacsimile machine 7 to finish receiving the pixel data earlier, ascompared with the case in which the process returns to theretransmission of the non-standard function signal NSF.

According to this embodiment, the minimum and necessary amount of pixeldata, which is determined by the communication rate negotiated betweenthe transmission side facsimile machine 1 a and the receiving sidefacsimile machine 7, is stored. This arrangement can prevent atransmission site identification signal TSI from being transmitted asmuch as possible before the minimum necessary amount of pixel data isaccumulated, even after the receipt of the receiving-ready confirmationsignal TSI. Consequently, accumulation of excessive amount of pixeldata, as well as communication errors due to inappropriate accumulationof pixel data, can be prevented. Thus, a stable and real-time facsimilecommunication can be achieved.

Although the present invention has been descried with reference to thespecific embodiments, the present invention is not limited to theseembodiments, and it will be apparent to those skilled in the art thatthere are many changes and substitutions which can be made withoutdeparting from the scope of the invention. Examples of such changes andsubstitutions are listed below.

(a) Although the LAN 4 or the IP network 50 are used as datacommunication networks in the embodiment, other types of datacommunication networks can be used.

(b) The facsimile procedure controller 14, the connection/transfercontroller 15, and the LAN controller 17 have been described asindependent elements in the embodiment. However, these elements may berealized as software executed by a single CPU. This can facilitate thehardware structure of the facsimile communication apparatus 10.

(c) Even if the facsimile machines 1 a and 7 employ non-standardprocedures which are not based on Recommendation T.30, continuous pixeldata transmission can be achieved, without interrupting the facsimilecommunication, by adjusting the pixel data transmission timing asdescribed in the embodiments.

Because the facsimile communication apparatus according to the firstinvention has a memory for temporarily storing a predetermined amount ofpixel packet signals received via a data communication network, stablefacsimile communication can be maintained without an unexpected breakupin the middle of transmission, even if the data-transfer rate differsbetween the transmission side facsimile machine 1 a and the receivingside facsimile machine 7. In addition, a mechanism for absorbing a delayin the UP network and for preventing excessive amount of accumulation ofpixel data is provided and, consequently, a facsimile communicationsystem having a high communication success rate (with littlecommunication error) can be achieved.

What is claimed is:
 1. A facsimile communication apparatus for receivingimage data from a transmission side facsimile machine via a datacommunication network, for temporarily storing the image data in amemory, and for transmitting the image data to a receiving sidefacsimile machine, the facsimile communication apparatus comprising:means for receiving the image data from the transmission side facsimilemachine via the data communication network and for temporarily storingthe received image data in the memory; and a waiting controller fortransmitting a prescribed wait control signal to the receiving sidefacsimile machine in order to have the receiving side facsimile machinestand by if a desirable amount of image data has not been stored in thememory at the time of receipt of a data receiving control signalrepresenting the acceptability of image data from the receiving sidefacsimile machine.
 2. The facsimile communication apparatus according toclaim 1, wherein the waiting controller comprises: determination meansfor determining whether or not the receiving side facsimile machine canwait in a data reception mode if the desirable amount of image data hasnot been stored in the memory at the time of receipt of thedata-receiving control signal; and waiting means for waiting for furtherstorage of image data until the desirable amount of image data is storedin the memory if the determination means determines that the receivingside facsimile machine can wait in a data acceptable state.
 3. Thefacsimile communication apparatus according to claim 1, wherein thewaiting controller comprises: determination means for determiningwhether or not the receiving side facsimile machine can wait in a datareception mode if the desirable amount of image data has not been storedin the memory at the time of receipt of the data-receiving controlsignal; and a wait control signal transmitter for transmitting the waitcontrol signal to the receiving side facsimile machine if thedetermination means determines that the receiving side facsimile machinecannot wait in the data reception mode.
 4. The facsimile communicationapparatus according to claim 1, further comprising calculation means forcalculating the desirable amount of image data stored in the memory bymultiplying the transmission rate of the image data determined bynegotiation between the transmission side facsimile machine and thereceiving side facsimile machine by a predetermined time stored inadvance.
 5. The facsimile communication apparatus according to claim 1,further comprising calculation means for calculating the desirableamount of image data stored in the memory by multiplying thecommunication rate determined by negotiation between the transmissionside facsimile machine and the receiving side facsimile machine by apredetermined time stored in advance.
 6. The facsimile communicationapparatus according to claim 1, wherein the transmission side facsimilemachine and the receiving side facsimile machine are G3 facsimilemachines categorized based on a T.30 Recommendation, the data-receivingcontrol signal comprises a data-receivable state confirmation signal CFRaccording to the T.30 Recommendation, and the wait control signalcomprises a transmission site identification signal TSI according to theT.30 Recommendation.
 7. A method for controlling a facsimilecommunication apparatus that receives image data from a transmissionside facsimile machine via a data communication network, temporarilystores the received image data in a memory, and transmits the image datato a receiving side facsimile machine, the method comprising the stepsof: (A) causing the facsimile communication apparatus to temporarilystore the image data received from the transmission side facsimilemachine via the data communication network in the memory; and (B)causing the facsimile communication apparatus to transmit a prescribedwait control signal to the receiving side facsimile machine in order tohave the receiving side facsimile machine stand by if the desirableamount of image data has not been stored in the memory at the time ofreceipt of a data-receiving control signal representing theacceptability of the image data from the receiving side facsimilemachine.
 8. The method according to claim 7, wherein the step (B)comprises the substeps of: (b1) causing the facsimile communicationapparatus to determine whether or mot the receiving side facsimilemachine can wait in a data reception mode if the desirable amount ofimage data has not been stored in the memory at the time of receipt ofthe data receiving control signal; and (b2) causing the facsimilecommunication apparatus to wait for further storage of image data untilthe desirable amount of image data is stored in the memory if it isdetermined in the substep (b1) that the receiving side facsimile machinecan wait in the data acceptable state.
 9. The method according to claim7, wherein the step (B) comprises the substeps of: (b1) causing thefacsimile communication apparatus to determine whether or not thereceiving side facsimile machine can wait in a data reception mode ifthe desirable amount of image data has not been stored in the memory atthe time of receipt of the data-receiving control signal; and (b3)causing the facsimile communication apparatus to transmit the waitcontrol signal to the receiving side facsimile machine if it isdetermined in the substep (b 1) that the receiving side facsimilemachine cannot wait in the data reception mode.
 10. The method accordingto claim 7, wherein the step (B) further comprises substep of: (b4)causing the facsimile communication apparatus to calculate the desirableamount of image data stored in the memory by multiplying thetransmission rate of the image data determined by negotiation betweenthe transmission side facsimile machine and the receiving side facsimilemachine by a predetermined time stored in advance.
 11. The methodaccording to claim 7, wherein the step (B) further comprises substep of:(b5) causing the facsimile communication apparatus to calculate thedesirable amount of image data stored in the memory by multiplying thecommunication rate determined by negotiation between the transmissionside facsimile machine and the receiving side facsimile machine by apredetermined time stored in advance.
 12. The program according to claim7, wherein the transmission side facsimile machine and the receivingside facsimile machine are G3 facsimile machines categorized based on aT.30 Recommendation, the data-receiving control signal comprises adata-receivable state confirmation signal CFR according to the T.30Recommendation, and the wait control signal comprises a transmissionsite identification signal TSI according to the T.30 Recommendation. 13.A method for controlling a facsimile communication apparatus thatreceives image data from a transmission side facsimile machine via adata communication network, temporarily stores the image data in amemory, and transits the image data to a receiving side facsimilemachine, the method comprising the steps of: (C) receiving the imagedata from the transmission side facsimile machine via the datacommunication network and temporarily storing the received image data inthe memory; and (D) transmitting a prescribed wait control signal to thereceiving side facsimile machine in order to have the receiving sidefacsimile machine stand by the desirable amount of image data has notbeen stored in the memory at the time of receipt of a data-receivingcontrol signal representing the acceptability of the image data from thereceiving side facsimile machine.
 14. The method for controlling afacsimile communication apparatus according to claim 13, wherein thestep (D) comprises the substeps of: (d1) determining whether or not thereceiving side facsimile machine can wait in a data reception mode ifthe desirable amount of image data has not been stored in the memory atthe time of receipt of the data-receiving control signal; and (d2)waiting for further storage of image data until the desirable amount ofimage data is stored in the memory if it is determined in the substep(d1) that the receiving side facsimile machine can wait in the dataacceptable state.
 15. The method according to claim 13, wherein the step(D) comprises the substeps of: (d1) determining whether or not thereceiving side facsimile machine can wait in a data reception mode ifthe desirable amount of image data has not been stored in the memory atthe time of receipt of the data-receiving control signal; and (d3)transmitting the wait control signal to the receiving side facsimilemachine if it is determined in the substep (d1) that the receiving sidefacsimile machine cannot wait in the data reception mode.
 16. The methodaccording to claim 13, wherein the step (D) further comprises thesubstep of: (d4) calculating the desirable amount of image data storedin the memory by multiplying the transmission rate of the image datadetermined by negotiation between the transmission side facsimilemachine and the receiving side facsimile machine by a predetermined timestored in advance.
 17. The method according to claim 13, wherein thestep (D) further comprises the substep of: (d5) calculating thedesirable amount of image data stored in the memory by multiplying thecommunication rate determined by negotiation between the transmissionside facsimile machine and the receiving side facsimile machine by apredetermined time stored in advance.
 18. The method according to claim13, wherein the transmission side facsimile machine and the receivingdata facsimile machine are G3 facsimile machines categorized based on aT.30 Recommendation, the data-receiving control signal comprises adata-receivable state confirmation signal CFR according to the T.30Recommendation, and the wait control signal comprises a transmissionsite identification Signal TSI according to the T.30 Recommendation.